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8054196: XPath: support any type

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Reviewed-by: alanb, lancea, dfuchs
This commit is contained in:
Joe Wang 2015-01-27 22:01:46 -08:00
parent 73a00f6b2f
commit 54b2d15c94
15 changed files with 2121 additions and 908 deletions
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401
jaxp/src/java.xml/share/classes/javax/xml/xpath/XPath.java
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2003, 2005, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2003, 2015, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -25,12 +25,12 @@
package javax.xml.xpath;
import org.xml.sax.InputSource;
import javax.xml.namespace.QName;
import javax.xml.namespace.NamespaceContext;
import javax.xml.namespace.QName;
import org.xml.sax.InputSource;
/**
* <p><code>XPath</code> provides access to the XPath evaluation environment and expressions.</p>
* {@code XPath} provides access to the XPath evaluation environment and expressions.
*
* <a name="XPath-evaluation"/>
* <table border="1" cellpadding="2">
@ -39,7 +39,6 @@ import javax.xml.namespace.NamespaceContext;
* <th colspan="2">Evaluation of XPath Expressions.</th>
* </tr>
* </thead>
* <tbody>
* <tr>
* <td>context</td>
* <td>
@ -55,8 +54,8 @@ import javax.xml.namespace.NamespaceContext;
* If the expression contains a variable reference, its value will be found through the {@link XPathVariableResolver}
* set with {@link #setXPathVariableResolver(XPathVariableResolver resolver)}.
* An {@link XPathExpressionException} is raised if the variable resolver is undefined or
* the resolver returns <code>null</code> for the variable.
* The value of a variable must be immutable through the course of any single evaluation.</p>
* the resolver returns {@code null} for the variable.
* The value of a variable must be immutable through the course of any single evaluation.
* </td>
* </tr>
* <tr>
@ -65,7 +64,7 @@ import javax.xml.namespace.NamespaceContext;
* If the expression contains a function reference, the function will be found through the {@link XPathFunctionResolver}
* set with {@link #setXPathFunctionResolver(XPathFunctionResolver resolver)}.
* An {@link XPathExpressionException} is raised if the function resolver is undefined or
* the function resolver returns <code>null</code> for the function.</p>
* the function resolver returns {@code null} for the function.
* </td>
* </tr>
* <tr>
@ -80,7 +79,7 @@ import javax.xml.namespace.NamespaceContext;
* <td>
* This result of evaluating an expression is converted to an instance of the desired return type.
* Valid return types are defined in {@link XPathConstants}.
* Conversion to the return type follows XPath conversion rules.</p>
* Conversion to the return type follows XPath conversion rules.
* </td>
* </tr>
* </table>
@ -88,9 +87,9 @@ import javax.xml.namespace.NamespaceContext;
* <p>An XPath object is not thread-safe and not reentrant.
* In other words, it is the application's responsibility to make
* sure that one {@link XPath} object is not used from
* more than one thread at any given time, and while the <code>evaluate</code>
* more than one thread at any given time, and while the {@code evaluate}
* method is invoked, applications may not recursively call
* the <code>evaluate</code> method.
* the {@code evaluate} method.
* <p>
*
* @author <a href="Norman.Walsh@Sun.com">Norman Walsh</a>
@ -100,191 +99,189 @@ import javax.xml.namespace.NamespaceContext;
*/
public interface XPath {
/**
* <p>Reset this <code>XPath</code> to its original configuration.</p>
*
* <p><code>XPath</code> is reset to the same state as when it was created with
* {@link XPathFactory#newXPath()}.
* <code>reset()</code> is designed to allow the reuse of existing <code>XPath</code>s
* thus saving resources associated with the creation of new <code>XPath</code>s.</p>
*
* <p>The reset <code>XPath</code> is not guaranteed to have the same {@link XPathFunctionResolver}, {@link XPathVariableResolver}
* or {@link NamespaceContext} <code>Object</code>s, e.g. {@link Object#equals(Object obj)}.
* It is guaranteed to have a functionally equal <code>XPathFunctionResolver</code>, <code>XPathVariableResolver</code>
* and <code>NamespaceContext</code>.</p>
*/
public void reset();
/**
* <p>Establish a variable resolver.</p>
* Reset this {@code XPath} to its original configuration.
*
* <p>A <code>NullPointerException</code> is thrown if <code>resolver</code> is <code>null</code>.</p>
* <p>{@code XPath} is reset to the same state as when it was created with
* {@link XPathFactory#newXPath()}.
* {@code reset()} is designed to allow the reuse of existing {@code XPath}s
* thus saving resources associated with the creation of new {@code XPath}s.
*
* <p>The reset {@code XPath} is not guaranteed to have the same
* {@link XPathFunctionResolver}, {@link XPathVariableResolver}
* or {@link NamespaceContext} {@code Object}s, e.g. {@link Object#equals(Object obj)}.
* It is guaranteed to have a functionally equal {@code XPathFunctionResolver},
* {@code XPathVariableResolver} and {@code NamespaceContext}.
*/
public void reset();
/**
* Establish a variable resolver.
*
* <p>A {@code NullPointerException} is thrown if {@code resolver} is {@code null}.
*
* @param resolver Variable resolver.
*
* @throws NullPointerException If <code>resolver</code> is <code>null</code>.
* @throws NullPointerException If {@code resolver} is {@code null}.
*/
public void setXPathVariableResolver(XPathVariableResolver resolver);
/**
* <p>Return the current variable resolver.</p>
* Return the current variable resolver.
*
* <p><code>null</code> is returned in no variable resolver is in effect.</p>
* <p>{@code null} is returned in no variable resolver is in effect.
*
* @return Current variable resolver.
*/
public XPathVariableResolver getXPathVariableResolver();
/**
* <p>Establish a function resolver.</p>
* Establish a function resolver.
*
* <p>A <code>NullPointerException</code> is thrown if <code>resolver</code> is <code>null</code>.</p>
* <p>A {@code NullPointerException} is thrown if {@code resolver} is {@code null}.
*
* @param resolver XPath function resolver.
*
* @throws NullPointerException If <code>resolver</code> is <code>null</code>.
* @throws NullPointerException If {@code resolver} is {@code null}.
*/
public void setXPathFunctionResolver(XPathFunctionResolver resolver);
/**
* <p>Return the current function resolver.</p>
*
* <p><code>null</code> is returned in no function resolver is in effect.</p>
* Return the current function resolver.
* <p>
* {@code null} is returned in no function resolver is in effect.
*
* @return Current function resolver.
*/
public XPathFunctionResolver getXPathFunctionResolver();
/**
* <p>Establish a namespace context.</p>
* Establish a namespace context.
*
* <p>A <code>NullPointerException</code> is thrown if <code>nsContext</code> is <code>null</code>.</p>
* <p>A {@code NullPointerException} is thrown if {@code nsContext} is {@code null}.
*
* @param nsContext Namespace context to use.
*
* @throws NullPointerException If <code>nsContext</code> is <code>null</code>.
* @throws NullPointerException If {@code nsContext} is {@code null}.
*/
public void setNamespaceContext(NamespaceContext nsContext);
/**
* <p>Return the current namespace context.</p>
* Return the current namespace context.
*
* <p><code>null</code> is returned in no namespace context is in effect.</p>
* <p>{@code null} is returned in no namespace context is in effect.
*
* @return Current Namespace context.
*/
public NamespaceContext getNamespaceContext();
/**
* <p>Compile an XPath expression for later evaluation.</p>
* Compile an XPath expression for later evaluation.
*
* <p>If <code>expression</code> contains any {@link XPathFunction}s,
* <p>If {@code expression} contains any {@link XPathFunction}s,
* they must be available via the {@link XPathFunctionResolver}.
* An {@link XPathExpressionException} will be thrown if the
* <code>XPathFunction</code>
* cannot be resovled with the <code>XPathFunctionResolver</code>.</p>
* {@code XPathFunction}
* cannot be resovled with the {@code XPathFunctionResolver}.
*
* <p>If <code>expression</code> contains any variables, the
* <p>If {@code expression} contains any variables, the
* {@link XPathVariableResolver} in effect
* <strong>at compile time</strong> will be used to resolve them.</p>
*
* <p>If <code>expression</code> is <code>null</code>, a <code>NullPointerException</code> is thrown.</p>
* <strong>at compile time</strong> will be used to resolve them.
*
* @param expression The XPath expression.
*
* @return Compiled XPath expression.
* @throws XPathExpressionException If <code>expression</code> cannot be compiled.
* @throws NullPointerException If <code>expression</code> is <code>null</code>.
* @throws XPathExpressionException If {@code expression} cannot be compiled.
* @throws NullPointerException If {@code expression} is {@code null}.
*/
public XPathExpression compile(String expression)
throws XPathExpressionException;
/**
* <p>Evaluate an <code>XPath</code> expression in the specified context and return the result as the specified type.</p>
* Evaluate an {@code XPath} expression in the specified context and
* return the result as the specified type.
*
* <p>See <a href="#XPath-evaluation">Evaluation of XPath Expressions</a> for context item evaluation,
* variable, function and <code>QName</code> resolution and return type conversion.</p>
* <p>
* See <a href="#XPath-evaluation">Evaluation of XPath Expressions</a>
* for context item evaluation, variable, function and {@code QName} resolution
* and return type conversion.
* <p>
* The parameter {@code item} represents the context the XPath expression
* will be operated on. The type of the context is implementation-dependent.
* If the value is {@code null}, the operation must have no dependency on
* the context, otherwise an XPathExpressionException will be thrown.
*
* <p>If <code>returnType</code> is not one of the types defined in {@link XPathConstants} (
* @implNote
* The type of the context is usually {@link org.w3c.dom.Node}.
*
* @param expression The XPath expression.
* @param item The context the XPath expression will be evaluated in.
* @param returnType The result type expected to be returned by the XPath expression.
*
* @return The result of evaluating an XPath expression as an {@code Object} of {@code returnType}.
*
* @throws XPathExpressionException If {@code expression} cannot be evaluated.
* @throws IllegalArgumentException If {@code returnType} is not one of the types defined in {@link XPathConstants} (
* {@link XPathConstants#NUMBER NUMBER},
* {@link XPathConstants#STRING STRING},
* {@link XPathConstants#BOOLEAN BOOLEAN},
* {@link XPathConstants#NODE NODE} or
* {@link XPathConstants#NODESET NODESET})
* then an <code>IllegalArgumentException</code> is thrown.</p>
*
* <p>If a <code>null</code> value is provided for
* <code>item</code>, an empty document will be used for the
* context.
* If <code>expression</code> or <code>returnType</code> is <code>null</code>, then a
* <code>NullPointerException</code> is thrown.</p>
*
* @param expression The XPath expression.
* @param item The starting context (a node, for example).
* @param returnType The desired return type.
*
* @return Result of evaluating an XPath expression as an <code>Object</code> of <code>returnType</code>.
*
* @throws XPathExpressionException If <code>expression</code> cannot be evaluated.
* @throws IllegalArgumentException If <code>returnType</code> is not one of the types defined in {@link XPathConstants}.
* @throws NullPointerException If <code>expression</code> or <code>returnType</code> is <code>null</code>.
* {@link XPathConstants#NODESET NODESET}).
* @throws NullPointerException If {@code expression or returnType} is {@code null}.
*/
public Object evaluate(String expression, Object item, QName returnType)
throws XPathExpressionException;
/**
* <p>Evaluate an XPath expression in the specified context and return the result as a <code>String</code>.</p>
* Evaluate an XPath expression in the specified context and return the result as a {@code String}.
*
* <p>This method calls {@link #evaluate(String expression, Object item, QName returnType)} with a <code>returnType</code> of
* {@link XPathConstants#STRING}.</p>
* <p>This method calls {@link #evaluate(String expression, Object item, QName returnType)} with a {@code returnType} of
* {@link XPathConstants#STRING}.
*
* <p>See <a href="#XPath-evaluation">Evaluation of XPath Expressions</a> for context item evaluation,
* variable, function and QName resolution and return type conversion.</p>
* variable, function and QName resolution and return type conversion.
*
* <p>If a <code>null</code> value is provided for
* <code>item</code>, an empty document will be used for the
* context.
* If <code>expression</code> is <code>null</code>, then a <code>NullPointerException</code> is thrown.</p>
* <p>
* The parameter {@code item} represents the context the XPath expression
* will be operated on. The type of the context is implementation-dependent.
* If the value is {@code null}, the operation must have no dependency on
* the context, otherwise an XPathExpressionException will be thrown.
*
* @implNote
* The type of the context is usually {@link org.w3c.dom.Node}.
*
* @param expression The XPath expression.
* @param item The starting context (a node, for example).
* @param item The context the XPath expression will be evaluated in.
*
* @return The <code>String</code> that is the result of evaluating the expression and
* converting the result to a <code>String</code>.
* @return The result of evaluating an XPath expression as a {@code String}.
*
* @throws XPathExpressionException If <code>expression</code> cannot be evaluated.
* @throws NullPointerException If <code>expression</code> is <code>null</code>.
* @throws XPathExpressionException If {@code expression} cannot be evaluated.
* @throws NullPointerException If {@code expression} is {@code null}.
*/
public String evaluate(String expression, Object item)
throws XPathExpressionException;
/**
* <p>Evaluate an XPath expression in the context of the specified <code>InputSource</code>
* and return the result as the specified type.</p>
* Evaluate an XPath expression in the context of the specified {@code InputSource}
* and return the result as the specified type.
*
* <p>This method builds a data model for the {@link InputSource} and calls
* {@link #evaluate(String expression, Object item, QName returnType)} on the resulting document object.</p>
* {@link #evaluate(String expression, Object item, QName returnType)} on the resulting document object.
*
* <p>See <a href="#XPath-evaluation">Evaluation of XPath Expressions</a> for context item evaluation,
* variable, function and QName resolution and return type conversion.</p>
*
* <p>If <code>returnType</code> is not one of the types defined in {@link XPathConstants},
* then an <code>IllegalArgumentException</code> is thrown.</p>
*
* <p>If <code>expression</code>, <code>source</code> or <code>returnType</code> is <code>null</code>,
* then a <code>NullPointerException</code> is thrown.</p>
* variable, function and QName resolution and return type conversion.
*
* @param expression The XPath expression.
* @param source The input source of the document to evaluate over.
* @param returnType The desired return type.
*
* @return The <code>Object</code> that encapsulates the result of evaluating the expression.
* @return The {@code Object} that encapsulates the result of evaluating the expression.
*
* @throws XPathExpressionException If expression cannot be evaluated.
* @throws IllegalArgumentException If <code>returnType</code> is not one of the types defined in {@link XPathConstants}.
* @throws NullPointerException If <code>expression</code>, <code>source</code> or <code>returnType</code>
* is <code>null</code>.
* @throws IllegalArgumentException If {@code returnType} is not one of the types defined in {@link XPathConstants}.
* @throws NullPointerException If {@code expression, source or returnType} is {@code null}.
*/
public Object evaluate(
String expression,
@ -293,27 +290,209 @@ public interface XPath {
throws XPathExpressionException;
/**
* <p>Evaluate an XPath expression in the context of the specified <code>InputSource</code>
* and return the result as a <code>String</code>.</p>
* Evaluate an XPath expression in the context of the specified {@code InputSource}
* and return the result as a {@code String}.
*
* <p>This method calls {@link #evaluate(String expression, InputSource source, QName returnType)} with a
* <code>returnType</code> of {@link XPathConstants#STRING}.</p>
* {@code returnType} of {@link XPathConstants#STRING}.
*
* <p>See <a href="#XPath-evaluation">Evaluation of XPath Expressions</a> for context item evaluation,
* variable, function and QName resolution and return type conversion.</p>
*
* <p>If <code>expression</code> or <code>source</code> is <code>null</code>,
* then a <code>NullPointerException</code> is thrown.</p>
* variable, function and QName resolution and return type conversion.
*
* @param expression The XPath expression.
* @param source The <code>InputSource</code> of the document to evaluate over.
* @param source The {@code InputSource} of the document to evaluate over.
*
* @return The <code>String</code> that is the result of evaluating the expression and
* converting the result to a <code>String</code>.
* @return The {@code String} that is the result of evaluating the expression and
* converting the result to a {@code String}.
*
* @throws XPathExpressionException If expression cannot be evaluated.
* @throws NullPointerException If <code>expression</code> or <code>source</code> is <code>null</code>.
* @throws NullPointerException If {@code expression or source} is {@code null}.
*/
public String evaluate(String expression, InputSource source)
throws XPathExpressionException;
/**
* Evaluate an XPath expression in the specified context and return
* the result with the type specified through the {@code class type}
*
* <p>
* The parameter {@code item} represents the context the XPath expression
* will be operated on. The type of the context is implementation-dependent.
* If the value is {@code null}, the operation must have no dependency on
* the context, otherwise an XPathExpressionException will be thrown.
*
* @implNote
* The type of the context is usually {@link org.w3c.dom.Node}.
*
* @implSpec
* The default implementation in the XPath API is equivalent to:
* <pre> {@code
* (T)evaluate(expression, item,
* XPathEvaluationResult.XPathResultType.getQNameType(type));
* }</pre>
*
* Since the {@code evaluate} method does not support the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type, specifying
* XPathEvaluationResult as the type will result in IllegalArgumentException.
* Any implementation supporting the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type must override
* this method.
*
* @param <T> The class type that will be returned by the XPath expression.
* @param expression The XPath expression.
* @param item The context the XPath expression will be evaluated in.
* @param type The class type expected to be returned by the XPath expression.
*
* @return The result of evaluating the expression.
*
* @throws XPathExpressionException If the expression cannot be evaluated.
* @throws IllegalArgumentException If {@code type} is not of the types
* corresponding to the types defined in the {@link XPathEvaluationResult.XPathResultType},
* or XPathEvaluationResult is specified as the type but an implementation supporting the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type is not available.
* @throws NullPointerException If {@code expression or type} is {@code null}.
*
* @since 1.9
*/
default <T>T evaluateExpression(String expression, Object item, Class<T> type)
throws XPathExpressionException {
return type.cast(evaluate(expression, item,
XPathEvaluationResult.XPathResultType.getQNameType(type)));
}
/**
* Evaluate an XPath expression in the specified context. This is equivalent to
* calling {@link #evaluateExpression(String expression, Object item, Class type)}
* with type {@link XPathEvaluationResult}:
* <pre> {@code
* evaluateExpression(expression, item, XPathEvaluationResult.class);
* }</pre>
* <p>
* The parameter {@code item} represents the context the XPath expression
* will be operated on. The type of the context is implementation-dependent.
* If the value is {@code null}, the operation must have no dependency on
* the context, otherwise an XPathExpressionException will be thrown.
*
* @implNote
* The type of the context is usually {@link org.w3c.dom.Node}.
*
* @implSpec
* The default implementation in the XPath API is equivalent to:
* <pre> {@code
* evaluateExpression(expression, item, XPathEvaluationResult.class);
* }</pre>
*
* Since the {@code evaluate} method does not support the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY}
* type, the default implementation of this method will always throw an
* IllegalArgumentException. Any implementation supporting the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type must therefore
* override this method.
*
* @param expression The XPath expression.
* @param item The context the XPath expression will be evaluated in.
*
* @return The result of evaluating the expression.
*
* @throws XPathExpressionException If the expression cannot be evaluated.
* @throws IllegalArgumentException If the implementation of this method
* does not support the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type.
* @throws NullPointerException If {@code expression} is {@code null}.
*
* @since 1.9
*/
default XPathEvaluationResult<?> evaluateExpression(String expression, Object item)
throws XPathExpressionException
{
return evaluateExpression(expression, item, XPathEvaluationResult.class);
}
/**
* Evaluate an XPath expression in the context of the specified {@code source}
* and return the result as specified.
* <p>
* This method builds a data model for the {@link InputSource} and calls
* {@link #evaluateExpression(String expression, Object item, Class type)}
* on the resulting document object. The data model is usually
* {@link org.w3c.dom.Document}
*
* @implSpec
* The default implementation in the XPath API is equivalent to:
* <pre> {@code
(T)evaluate(expression, source,
XPathEvaluationResult.XPathResultType.getQNameType(type));
* }</pre>
*
* Since the {@code evaluate} method does not support the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type, specifying
* XPathEvaluationResult as the type will result in IllegalArgumentException.
* Any implementation supporting the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type must override
* this method.
*
* @param <T> The class type that will be returned by the XPath expression.
* @param expression The XPath expression.
* @param source The input source of the document to evaluate over.
* @param type The class type expected to be returned by the XPath expression.
*
* @return The result of evaluating the expression.
*
* @throws XPathExpressionException If the expression cannot be evaluated.
* @throws IllegalArgumentException If {@code type} is not of the types
* corresponding to the types defined in the {@link XPathEvaluationResult.XPathResultType
* XPathResultType}, or XPathEvaluationResult is specified as the type but an
* implementation supporting the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type is not available.
* @throws NullPointerException If {@code expression, source or type}is {@code null}.
*
* @since 1.9
*/
default <T>T evaluateExpression(String expression, InputSource source, Class<T> type)
throws XPathExpressionException
{
return type.cast(evaluate(expression, source,
XPathEvaluationResult.XPathResultType.getQNameType(type)));
}
/**
* Evaluate an XPath expression in the specified context. This is equivalent to
* calling {@link #evaluateExpression(String expression, Object item, Class type)}
* with type {@link XPathEvaluationResult}:
* <pre> {@code
* evaluateExpression(expression, item, XPathEvaluationResult.class);
* }</pre>
* <p>
*
* @implSpec
* The default implementation in the XPath API is equivalent to:
* <pre> {@code
* evaluateExpression(expression, source, XPathEvaluationResult.class);
* }</pre>
*
* Since the {@code evaluate} method does not support the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY}
* type, the default implementation of this method will always throw an
* IllegalArgumentException. Any implementation supporting the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type must therefore
* override this method.
*
* @param expression The XPath expression.
* @param source The input source of the document to evaluate over.
*
* @return The result of evaluating the expression.
*
* @throws XPathExpressionException If the expression cannot be evaluated.
* @throws IllegalArgumentException If the implementation of this method
* does not support the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type.
* @throws NullPointerException If {@code expression or source} is {@code null}.
*
* @since 1.9
*/
default XPathEvaluationResult<?> evaluateExpression(String expression, InputSource source)
throws XPathExpressionException
{
return evaluateExpression(expression, source, XPathEvaluationResult.class);
}
}

130
jaxp/src/java.xml/share/classes/javax/xml/xpath/XPathEvaluationResult.java Normal file
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@ -0,0 +1,130 @@
/*
* Copyright (c) 2015 Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package javax.xml.xpath;
import java.util.Objects;
import javax.xml.namespace.QName;
import org.w3c.dom.Node;
/**
* The {@code XPathEvaluationResult} interface represents the result of the
* evaluation of an XPath expression within the context of a particular node.
* The evaluation of an XPath expression can result in various result types as
* defined in XML Path Language (XPath) Version 1.0.
* <p>
*
* @param <T> the object type returned by the XPath evaluation.
* @see <a href="http://www.w3.org/TR/xpath">XML Path Language (XPath) Version
* 1.0</a>
*
* @since 1.9
*/
public interface XPathEvaluationResult<T> {
/**
* XPathResultType represents possible return types of an XPath evaluation.
* Provided as an enum type, it allows the use of switch statement. At the
* same time, a mapping is provided between the original QName types in
* {@link XPathConstants} and class types used in the generic methods.
*/
public static enum XPathResultType {
/**
* Any type that represents any of the 5 other types listed below.
* Maps to {@link XPathEvaluationResult}.
*/
ANY(new QName("http://www.w3.org/1999/XSL/Transform", "any"), XPathEvaluationResult.class),
/**
* The XPath 1.0 boolean data type. Maps to Java {@link Boolean}.
*/
BOOLEAN(XPathConstants.BOOLEAN, Boolean.class),
/**
* The XPath 1.0 Number data type. Maps to Java {@link Number}. Of the
* subtypes of Number, only Double, Integer and Long are required.
*/
NUMBER(XPathConstants.NUMBER, Number.class),
/**
* The XPath 1.0 String data type. Maps to Java {@link String}.
*/
STRING(XPathConstants.STRING, String.class),
/**
* The XPath 1.0 NodeSet data type. Maps to {@link org.w3c.dom.NodeList}.
*/
NODESET(XPathConstants.NODESET, XPathNodes.class),
/**
* The XPath 1.0 NodeSet data type. Maps to {@link org.w3c.dom.Node}.
*/
NODE(XPathConstants.NODE, Node.class);
final QName qnameType;
final Class<?> clsType;
XPathResultType(QName qnameType, Class<?> clsType) {
this.qnameType = qnameType;
this.clsType = clsType;
}
/**
* Compares this type to the specified class type.
* @param clsType class type
* @return true if the argument is not null and is a class type that
* matches that this type represents, false otherwise.
*/
private boolean equalsClassType(Class<?> clsType) {
Objects.nonNull(clsType);
if (clsType.isAssignableFrom(this.clsType)) {
return true;
}
return false;
}
/**
* Returns the QName type as specified in {@link XPathConstants} that
* corresponds to the specified class type.
* @param clsType a class type that the enum type supports
* @return the QName type that matches with the specified class type,
* null if there is no match
*/
static public QName getQNameType(Class<?> clsType) {
for (XPathResultType type : XPathResultType.values()) {
if (type.equalsClassType(clsType)) {
return type.qnameType;
}
}
return null;
}
}
/**
* Return the result type as an enum specified by {@code XPathResultType}
* @return the result type
*/
public XPathResultType type();
/**
* Returns the value of the result as the type &lt;T&gt; specified for the class.
*
* @return The value of the result.
*/
public T value();
}

276
jaxp/src/java.xml/share/classes/javax/xml/xpath/XPathExpression.java
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2003, 2005, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2003, 2015, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -25,11 +25,11 @@
package javax.xml.xpath;
import org.xml.sax.InputSource;
import javax.xml.namespace.QName;
import org.xml.sax.InputSource;
/**
* <p><code>XPathExpression</code> provides access to compiled XPath expressions.</p>
* <p>{@code XPathExpression} provides access to compiled XPath expressions.</p>
*
* <a name="XPathExpression-evaluation"/>
* <table border="1" cellpadding="2">
@ -53,7 +53,7 @@ import javax.xml.namespace.QName;
* <td>
* If the expression contains a variable reference, its value will be found through the {@link XPathVariableResolver}.
* An {@link XPathExpressionException} is raised if the variable resolver is undefined or
* the resolver returns <code>null</code> for the variable.
* the resolver returns {@code null} for the variable.
* The value of a variable must be immutable through the course of any single evaluation.</p>
* </td>
* </tr>
@ -62,7 +62,7 @@ import javax.xml.namespace.QName;
* <td>
* If the expression contains a function reference, the function will be found through the {@link XPathFunctionResolver}.
* An {@link XPathExpressionException} is raised if the function resolver is undefined or
* the function resolver returns <code>null</code> for the function.</p>
* the function resolver returns {@code null} for the function.</p>
* </td>
* </tr>
* <tr>
@ -84,9 +84,9 @@ import javax.xml.namespace.QName;
* <p>An XPath expression is not thread-safe and not reentrant.
* In other words, it is the application's responsibility to make
* sure that one {@link XPathExpression} object is not used from
* more than one thread at any given time, and while the <code>evaluate</code>
* more than one thread at any given time, and while the {@code evaluate}
* method is invoked, applications may not recursively call
* the <code>evaluate</code> method.
* the {@code evaluate} method.
* <p>
*
* @author <a href="mailto:Norman.Walsh@Sun.com">Norman Walsh</a>
@ -96,50 +96,56 @@ import javax.xml.namespace.QName;
*/
public interface XPathExpression {
/**
* <p>Evaluate the compiled XPath expression in the specified context and return the result as the specified type.</p>
*
* <p>See <a href="#XPathExpression-evaluation">Evaluation of XPath Expressions</a> for context item evaluation,
* variable, function and QName resolution and return type conversion.</p>
*
* <p>If <code>returnType</code> is not one of the types defined in {@link XPathConstants},
* then an <code>IllegalArgumentException</code> is thrown.</p>
* <p>
* The parameter {@code item} represents the context the XPath expression
* will be operated on. The type of the context is implementation-dependent.
* If the value is {@code null}, the operation must have no dependency on
* the context, otherwise an XPathExpressionException will be thrown.
*
* <p>If a <code>null</code> value is provided for
* <code>item</code>, an empty document will be used for the
* context.
* If <code>returnType</code> is <code>null</code>, then a <code>NullPointerException</code> is thrown.</p>
* @implNote
* The type of the context is usually {@link org.w3c.dom.Node}.
*
* @param item The starting context (a node, for example).
* @param returnType The desired return type.
* @param item The context the XPath expression will be evaluated in.
* @param returnType The result type expected to be returned by the XPath expression.
*
* @return The <code>Object</code> that is the result of evaluating the expression and converting the result to
* <code>returnType</code>.
* @return The {@code Object} that is the result of evaluating the expression and converting the result to
* {@code returnType}.
*
* @throws XPathExpressionException If the expression cannot be evaluated.
* @throws IllegalArgumentException If <code>returnType</code> is not one of the types defined in {@link XPathConstants}.
* @throws NullPointerException If <code>returnType</code> is <code>null</code>.
* @throws IllegalArgumentException If {@code returnType} is not one of the types defined in {@link XPathConstants}.
* @throws NullPointerException If {@code returnType} is {@code null}.
*/
public Object evaluate(Object item, QName returnType)
throws XPathExpressionException;
/**
* <p>Evaluate the compiled XPath expression in the specified context and return the result as a <code>String</code>.</p>
* <p>Evaluate the compiled XPath expression in the specified context and return the result as a {@code String}.</p>
*
* <p>This method calls {@link #evaluate(Object item, QName returnType)} with a <code>returnType</code> of
* <p>This method calls {@link #evaluate(Object item, QName returnType)} with a {@code returnType} of
* {@link XPathConstants#STRING}.</p>
*
* <p>See <a href="#XPathExpression-evaluation">Evaluation of XPath Expressions</a> for context item evaluation,
* variable, function and QName resolution and return type conversion.</p>
*
* <p>If a <code>null</code> value is provided for
* <code>item</code>, an empty document will be used for the
* context.
* <p>
* The parameter {@code item} represents the context the XPath expression
* will be operated on. The type of the context is implementation-dependent.
* If the value is {@code null}, the operation must have no dependency on
* the context, otherwise an XPathExpressionException will be thrown.
*
* @param item The starting context (a node, for example).
* @implNote
* The type of the context is usually {@link org.w3c.dom.Node}.
*
* @return The <code>String</code> that is the result of evaluating the expression and converting the result to a
* <code>String</code>.
* @param item The context the XPath expression will be evaluated in.
*
* @return The result of evaluating an XPath expression as a {@code String}.
*
* @throws XPathExpressionException If the expression cannot be evaluated.
*/
@ -147,7 +153,7 @@ public interface XPathExpression {
throws XPathExpressionException;
/**
* <p>Evaluate the compiled XPath expression in the context of the specified <code>InputSource</code> and return the result as the
* <p>Evaluate the compiled XPath expression in the context of the specified {@code InputSource} and return the result as the
* specified type.</p>
*
* <p>This method builds a data model for the {@link InputSource} and calls
@ -156,45 +162,225 @@ public interface XPathExpression {
* <p>See <a href="#XPathExpression-evaluation">Evaluation of XPath Expressions</a> for context item evaluation,
* variable, function and QName resolution and return type conversion.</p>
*
* <p>If <code>returnType</code> is not one of the types defined in {@link XPathConstants},
* then an <code>IllegalArgumentException</code> is thrown.</p>
* <p>If {@code returnType} is not one of the types defined in {@link XPathConstants},
* then an {@code IllegalArgumentException} is thrown.</p>
*
* <p>If <code>source</code> or <code>returnType</code> is <code>null</code>,
* then a <code>NullPointerException</code> is thrown.</p>
* <p>If {@code source} or {@code returnType} is {@code null},
* then a {@code NullPointerException} is thrown.</p>
*
* @param source The <code>InputSource</code> of the document to evaluate over.
* @param source The {@code InputSource} of the document to evaluate over.
* @param returnType The desired return type.
*
* @return The <code>Object</code> that is the result of evaluating the expression and converting the result to
* <code>returnType</code>.
* @return The {@code Object} that is the result of evaluating the expression and converting the result to
* {@code returnType}.
*
* @throws XPathExpressionException If the expression cannot be evaluated.
* @throws IllegalArgumentException If <code>returnType</code> is not one of the types defined in {@link XPathConstants}.
* @throws NullPointerException If <code>source</code> or <code>returnType</code> is <code>null</code>.
* @throws IllegalArgumentException If {@code returnType} is not one of the types defined in {@link XPathConstants}.
* @throws NullPointerException If {@code source or returnType} is {@code null}.
*/
public Object evaluate(InputSource source, QName returnType)
throws XPathExpressionException;
/**
* <p>Evaluate the compiled XPath expression in the context of the specified <code>InputSource</code> and return the result as a
* <code>String</code>.</p>
* <p>Evaluate the compiled XPath expression in the context of the specified {@code InputSource} and return the result as a
* {@code String}.</p>
*
* <p>This method calls {@link #evaluate(InputSource source, QName returnType)} with a <code>returnType</code> of
* <p>This method calls {@link #evaluate(InputSource source, QName returnType)} with a {@code returnType} of
* {@link XPathConstants#STRING}.</p>
*
* <p>See <a href="#XPathExpression-evaluation">Evaluation of XPath Expressions</a> for context item evaluation,
* variable, function and QName resolution and return type conversion.</p>
*
* <p>If <code>source</code> is <code>null</code>, then a <code>NullPointerException</code> is thrown.</p>
* <p>If {@code source} is {@code null}, then a {@code NullPointerException} is thrown.</p>
*
* @param source The <code>InputSource</code> of the document to evaluate over.
* @param source The {@code InputSource} of the document to evaluate over.
*
* @return The <code>String</code> that is the result of evaluating the expression and converting the result to a
* <code>String</code>.
* @return The {@code String} that is the result of evaluating the expression and converting the result to a
* {@code String}.
*
* @throws XPathExpressionException If the expression cannot be evaluated.
* @throws NullPointerException If <code>source</code> is <code>null</code>.
* @throws NullPointerException If {@code source} is {@code null}.
*/
public String evaluate(InputSource source)
throws XPathExpressionException;
/**
* Evaluate the compiled XPath expression in the specified context, and return
* the result with the type specified through the {@code class type}.
*
* <p>
* The parameter {@code item} represents the context the XPath expression
* will be operated on. The type of the context is implementation-dependent.
* If the value is {@code null}, the operation must have no dependency on
* the context, otherwise an XPathExpressionException will be thrown.
*
* @implNote
* The type of the context is usually {@link org.w3c.dom.Node}.
*
* @implSpec
* The default implementation in the XPath API is equivalent to:
* <pre> {@code
* (T)evaluate(item, XPathEvaluationResult.XPathResultType.getQNameType(type));
* }</pre>
*
* Since the {@code evaluate} method does not support the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type, specifying
* XPathEvaluationResult as the type will result in IllegalArgumentException.
* Any implementation supporting the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type must override
* this method.
*
* @param <T> The class type that will be returned by the XPath expression.
* @param item The context the XPath expression will be evaluated in.
* @param type The class type expected to be returned by the XPath expression.
*
* @return The result of evaluating the expression.
*
* @throws XPathExpressionException If the expression cannot be evaluated.
* @throws IllegalArgumentException If {@code type} is not of the types
* corresponding to the types defined in the {@link XPathEvaluationResult.XPathResultType
* XPathResultType}, or XPathEvaluationResult is specified as the type but an
* implementation supporting the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type is not available.
* @throws NullPointerException If {@code type} is {@code null}.
*
* @since 1.9
*/
default <T>T evaluateExpression(Object item, Class<T> type)
throws XPathExpressionException
{
return type.cast(evaluate(item, XPathEvaluationResult.XPathResultType.getQNameType(type)));
}
/**
* Evaluate the compiled XPath expression in the specified context. This is
* equivalent to calling {@link #evaluateExpression(Object item, Class type)}
* with type {@link XPathEvaluationResult}:
* <pre> {@code
* evaluateExpression(item, XPathEvaluationResult.class);
* }</pre>
* <p>
* The parameter {@code item} represents the context the XPath expression
* will be operated on. The type of the context is implementation-dependent.
* If the value is {@code null}, the operation must have no dependency on
* the context, otherwise an XPathExpressionException will be thrown.
*
* @implNote
* The type of the context is usually {@link org.w3c.dom.Node}.
*
* @implSpec
* The default implementation in the XPath API is equivalent to:
* <pre> {@code
* evaluateExpression(item, XPathEvaluationResult.class);
* }</pre>
*
* Since the {@code evaluate} method does not support the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY}
* type, the default implementation of this method will always throw an
* IllegalArgumentException. Any implementation supporting the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type must therefore
* override this method.
*
* @param item The context the XPath expression will be evaluated in.
*
* @return The result of evaluating the expression.
*
* @throws XPathExpressionException If the expression cannot be evaluated.
* @throws IllegalArgumentException If the implementation of this method
* does not support the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type.
*
* @since 1.9
*/
default XPathEvaluationResult<?> evaluateExpression(Object item)
throws XPathExpressionException
{
return evaluateExpression(item, XPathEvaluationResult.class);
}
/**
* Evaluate the compiled XPath expression in the specified context,
* and return the result with the type specified through the {@code class type}
* <p>
* This method builds a data model for the {@link InputSource} and calls
* {@link #evaluateExpression(Object item, Class type)} on the resulting
* document object.
* <P>
* By default, the JDK's data model is {@link org.w3c.dom.Document}.
*
* @implSpec
* The default implementation in the XPath API is equivalent to:
* <pre> {@code
(T)evaluate(source, XPathEvaluationResult.XPathResultType.getQNameType(type));
* }</pre>
*
* Since the {@code evaluate} method does not support the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type, specifying
* XPathEvaluationResult as the type will result in IllegalArgumentException.
* Any implementation supporting the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type must override
* this method.
*
* @param <T> The class type that will be returned by the XPath expression.
* @param source The {@code InputSource} of the document to evaluate over.
* @param type The class type expected to be returned by the XPath expression.
*
* @return The result of evaluating the expression.
*
* @throws XPathExpressionException If the expression cannot be evaluated.
* @throws IllegalArgumentException If {@code type} is not of the types
* corresponding to the types defined in the {@link XPathEvaluationResult.XPathResultType
* XPathResultType}, or XPathEvaluationResult is specified as the type but an
* implementation supporting the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type
* is not available.
* @throws NullPointerException If {@code source or type} is {@code null}.
*
* @since 1.9
*/
default <T>T evaluateExpression(InputSource source, Class<T> type)
throws XPathExpressionException
{
return type.cast(evaluate(source, XPathEvaluationResult.XPathResultType.getQNameType(type)));
}
/**
* Evaluate the compiled XPath expression in the specified context. This is
* equivalent to calling {@link #evaluateExpression(InputSource source, Class type)}
* with type {@link XPathEvaluationResult}:
* <pre> {@code
* evaluateExpression(source, XPathEvaluationResult.class);
* }</pre>
* <p>
*
* @implSpec
* The default implementation in the XPath API is equivalent to:
* <pre> {@code
* (XPathEvaluationResult)evaluateExpression(source, XPathEvaluationResult.class);
* }</pre>
*
* Since the {@code evaluate} method does not support the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY}
* type, the default implementation of this method will always throw an
* IllegalArgumentException. Any implementation supporting the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type must therefore
* override this method.
*
* @param source The {@code InputSource} of the document to evaluate over.
*
* @return The result of evaluating the expression.
*
* @throws XPathExpressionException If the expression cannot be evaluated.
* @throws IllegalArgumentException If the implementation of this method
* does not support the
* {@link XPathEvaluationResult.XPathResultType#ANY ANY} type.
* @throws NullPointerException If {@code source} is {@code null}.
*
* @since 1.9
*/
default XPathEvaluationResult<?> evaluateExpression(InputSource source)
throws XPathExpressionException
{
return evaluateExpression(source, XPathEvaluationResult.class);
}
}

2
jaxp/src/java.xml/share/classes/javax/xml/xpath/XPathFactory.java
View file

@ -117,7 +117,7 @@ public abstract class XPathFactory {
* and returns it if it is successfully created.
* </li>
* <li>
* ${java.home}/conf/jaxp.properties is read and the value associated with the key being the system property above is looked for.
* ${java.home}/lib/jaxp.properties is read and the value associated with the key being the system property above is looked for.
* If present, the value is processed just like above.
* </li>
* <li>

6
jaxp/src/java.xml/share/classes/javax/xml/xpath/XPathFactoryFinder.java
View file

@ -176,9 +176,9 @@ class XPathFactoryFinder {
String javah = ss.getSystemProperty( "java.home" );
String configFile = javah + File.separator +
"conf" + File.separator + "jaxp.properties";
"lib" + File.separator + "jaxp.properties";
// try to read from $java.home/conf/jaxp.properties
// try to read from $java.home/lib/jaxp.properties
try {
if(firstTime){
synchronized(cacheProps){
@ -193,7 +193,7 @@ class XPathFactoryFinder {
}
}
final String factoryClassName = cacheProps.getProperty(propertyName);
debugPrintln("found " + factoryClassName + " in $java.home/conf/jaxp.properties");
debugPrintln("found " + factoryClassName + " in $java.home/jaxp.properties");
if (factoryClassName != null) {
xpathFactory = createInstance(factoryClassName, true);

65
jaxp/src/java.xml/share/classes/javax/xml/xpath/XPathNodes.java Normal file
View file

@ -0,0 +1,65 @@
/*
* Copyright (c) 2015 Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package javax.xml.xpath;
import java.util.Iterator;
import org.w3c.dom.Node;
/**
* XPathNodes represents a set of nodes selected by a location path as specified
* in <a href="http://www.w3.org/TR/xpath/#node-sets">XML Path Language (XPath)
* Version 1.0, 3.3 Node-sets</a>.
*
* @since 1.9
*/
public interface XPathNodes extends Iterable<Node> {
/**
* Returns an iterator of the Nodes.
*
* @return an Iterator.
*/
@Override
public abstract Iterator<Node> iterator();
/**
* Returns the number of items in the result
*
* @return The number of items in the result
*/
public abstract int size();
/**
* Returns a Node at the specified position
*
* @param index Index of the element to return.
* @return The Node at the specified position.
* @throws javax.xml.xpath.XPathException If the index is out of range
* (index &lt; 0 || index &gt;= size())
*/
public abstract Node get(int index)
throws XPathException;
}

236
jaxp/src/java.xml/share/classes/javax/xml/xpath/package.html
View file

@ -1,6 +1,8 @@
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
<html>
<head>
<!--
Copyright (c) 2003, 2005, Oracle and/or its affiliates. All rights reserved.
Copyright (c) 2003, 2015, Oracle and/or its affiliates. All rights reserved.
DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
This code is free software; you can redistribute it and/or modify it
@ -23,35 +25,35 @@ Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
or visit www.oracle.com if you need additional information or have any
questions.
-->
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>javax.xml.xpath</title>
<meta name="@author" content="mailto:Ben@galbraiths.org" />
<meta name="@author" content="mailto:Norman.Walsh@Sun.com" />
<meta name="@author" content="mailto:Jeff.Suttor@Sun.com" />
<meta name="@see" content="http://www.w3.org/TR/xpath" />
<meta name="@since" content="1.5" />
</head>
<body bgcolor="white">
<body>
<p>This package provides an <em>object-model neutral</em> API for the
This package provides an <em>object-model neutral</em> API for the
evaluation of XPath expressions and access to the evaluation
environment.
</p>
<p>The following XML standards apply:</p>
<ul>
<li><a href="http://www.w3.org/TR/xpath">XML Path Language (XPath) Version 1.0</a></li>
</ul>
<p>
The XPath API supports <a href="http://www.w3.org/TR/xpath">
XML Path Language (XPath) Version 1.0</a>
<hr />
<h2>XPath Overview</h2>
<ul>
<li><a href='#XPath.Overview'>1. XPath Overview</a></li>
<li><a href='#XPath.Expressions'>2. XPath Expressions</a></li>
<li><a href='#XPath.Datatypes'>3. XPath Data Types</a>
<ul>
<li><a href='#XPath.Datatypes.QName'>3.1 QName Types</a>
<li><a href='#XPath.Datatypes.Class'>3.2 Class Types</a>
<li><a href='#XPath.Datatypes.Enum'>3.3 Enum Types</a>
</ul>
</li>
<li><a href='#XPath.Context'>4. XPath Context</a></li>
<li><a href='#XPath.Use'>5. Using the XPath API</a></li>
</ul>
<p>
<a name="XPath.Overview"></a>
<h3>1. XPath Overview</h3>
<p>The XPath language provides a simple, concise syntax for selecting
nodes from an XML document. XPath also provides rules for converting a
@ -67,7 +69,8 @@ stand-alone language, as a single XPath expression can be used to
replace many lines of DOM API code.
</p>
<h3>XPath Expressions</h3>
<a name="XPath.Expressions"></a>
<h3>2. XPath Expressions</h3>
<p>An XPath <em>expression</em> is composed of a <em>location
path</em> and one or more optional <em>predicates</em>. Expressions
@ -76,18 +79,22 @@ may also include XPath variables.
<p>The following is an example of a simple XPath expression:</p>
<blockquote>
<pre>
/foo/bar
</pre>
</blockquote>
<p>This example would select the <code>&lt;bar&gt;</code> element in
an XML document such as the following:</p>
<blockquote>
<pre>
&lt;foo&gt;
&lt;bar/&gt;
&lt;bar/&gt;
&lt;/foo&gt;
</pre>
</blockquote>
<p>The expression <code>/foo/bar</code> is an example of a location
path. While XPath location paths resemble Unix-style file system
@ -96,30 +103,36 @@ paths, an important distinction is that XPath expressions return
<code>&lt;bar&gt;</code> elements in the following document would be
selected by the <code>/foo/bar</code> expression:</p>
<blockquote>
<pre>
&lt;foo&gt;
&lt;bar/&gt;
&lt;bar/&gt;
&lt;bar/&gt;
&lt;bar/&gt;
&lt;bar/&gt;
&lt;bar/&gt;
&lt;/foo&gt;
</pre>
</blockquote>
<p>A special location path operator, <code>//</code>, selects nodes at
any depth in an XML document. The following example selects all
<code>&lt;bar&gt;</code> elements regardless of their location in a
document:</p>
<blockquote>
<pre>
//bar
</pre>
</blockquote>
<p>A wildcard operator, *, causes all element nodes to be selected.
The following example selects all children elements of a
<code>&lt;foo&gt;</code> element:</p>
<code>&lt;foo&gt;</code> element:
<blockquote>
<pre>
/foo/*
</pre>
</blockquote>
<p>In addition to element nodes, XPath location paths may also address
attribute nodes, text nodes, comment nodes, and processing instruction
@ -166,35 +179,27 @@ location path. Predicates are of the form
<code>&lt;foo&gt;</code> elements that contain an <code>include</code>
attribute with the value of <code>true</code>:</p>
<blockquote>
<pre>
//foo[@include='true']
</pre>
</blockquote>
<p>Predicates may be appended to each other to further refine an
expression, such as:</p>
<blockquote>
<pre>
//foo[@include='true'][@mode='bar']
</pre>
</blockquote>
<h3>Using the XPath API</h3>
<p>
The following example demonstrates using the XPath API to select one
or more nodes from an XML document:</p>
<pre>
XPath xpath = XPathFactory.newInstance().newXPath();
String expression = "/widgets/widget";
InputSource inputSource = new InputSource("widgets.xml");
NodeList nodes = (NodeList) xpath.evaluate(expression, inputSource, XPathConstants.NODESET);
</pre>
<h3>XPath Expressions and Types</h3>
<a name="XPath.Datatypes"></a>
<h3>3. XPath Data Types</h3>
<p>While XPath expressions select nodes in the XML document, the XPath
API allows the selected nodes to be coalesced into one of the
following other data types:</p>
following data types:</p>
<ul>
<li><code>Boolean</code></li>
@ -202,14 +207,10 @@ following other data types:</p>
<li><code>String</code></li>
</ul>
<p>The desired return type is specified by a {@link
javax.xml.namespace.QName} parameter in method call used to evaluate
the expression, which is either a call to
<code>XPathExpression.evalute(...)</code> or to one of the
<code>XPath.evaluate(...)</code> convenience methods. The allowed
QName values are specified as constants in the {@link
javax.xml.xpath.XPathConstants} class; they are:</p>
<a name="XPath.Datatypes.QName"></a>
<h3>3.1 QName types</h3>
The XPath API defines the following {@link javax.xml.namespace.QName} types to
represent return types of an XPath evaluation:
<ul>
<li>{@link javax.xml.xpath.XPathConstants#NODESET}</li>
<li>{@link javax.xml.xpath.XPathConstants#NODE}</li>
@ -218,26 +219,71 @@ javax.xml.xpath.XPathConstants} class; they are:</p>
<li>{@link javax.xml.xpath.XPathConstants#NUMBER}</li>
</ul>
<p>The return type is specified by a {@link javax.xml.namespace.QName} parameter
in method call used to evaluate the expression, which is either a call to
<code>XPathExpression.evalute(...)</code> or <code>XPath.evaluate(...)</code>
methods.
<p>When a <code>Boolean</code> return type is requested,
<code>Boolean.TRUE</code> is returned if one or more nodes were
selected; otherwise, <code>Boolean.FALSE</code> is returned.</p>
selected; otherwise, <code>Boolean.FALSE</code> is returned.
<p>The <code>String</code> return type is a convenience for retrieving
the character data from a text node, attribute node, comment node, or
processing-instruction node. When used on an element node, the value
of the child text nodes is returned.
</p>
<p>The <code>Number</code> return type attempts to coalesce the text
of a node to a <code>double</code> data type.
</p>
<h3>XPath Context</h3>
<a name="XPath.Datatypes.Class"></a>
<h3>3.2 Class types</h3>
In addition to the QName types, the XPath API supports the use of Class types
through the <code>XPathExpression.evaluteExpression(...)</code> or
<code>XPath.evaluateExpression(...)</code> methods.
The XPath data types are mapped to Class types as follows:
<ul>
<li><code>Boolean</code> -- <code>Boolean.class</code></li>
<li><code>Number</code> -- <code>Number.class</code></li>
<li><code>String</code> -- <code>String.class</code></li>
<li><code>Nodeset</code> -- <code>XPathNodes.class</code></li>
<li><code>Node</code> -- <code>Node.class</code></li>
</ul>
<p>
Of the subtypes of Number, only Double, Integer and Long are supported.
<a name="XPath.Datatypes.Enum"></a>
<h3>3.3 Enum types</h3>
Enum types are defined in {@link javax.xml.xpath.XPathEvaluationResult.XPathResultType}
that provide mappings between the QName and Class types above. The result of
evaluating an expression using the <code>XPathExpression.evaluteExpression(...)</code>
or <code>XPath.evaluateExpression(...)</code> methods will be of one of these types.
<a name="XPath.Context"></a>
<h3>4. XPath Context</h3>
<p>XPath location paths may be relative to a particular node in the
document, known as the <code>context</code>. Consider the following
XML document:</p>
document, known as the <code>context</code>. A context consists of:
<ul>
<li>a node (the context node)</li>
<li>a pair of non-zero positive integers (the context position and the context size)</li>
<li>a set of variable bindings</li>
<li>a function library</li>
<li>the set of namespace declarations in scope for the expression</li>
</ul>
<p>
It is an XML document tree represented as a hierarchy of nodes, a
{@link org.w3c.dom.Node} for example, in the JDK implementation.
<a name="XPath.Use"></a>
<h3>5. Using the XPath API</h3>
Consider the following XML document:
<p>
<blockquote>
<pre>
&lt;widgets&gt;
&lt;widget&gt;
@ -246,36 +292,88 @@ XML document:</p>
&lt;/widget&gt;
&lt;/widgets&gt;
</pre>
</blockquote>
<p>The <code>&lt;widget&gt;</code> element can be selected with the
following XPath API code:</p>
<p>
The <code>&lt;widget&gt;</code> element can be selected with the following process:
<blockquote>
<pre>
// parse the XML as a W3C Document
DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document document = builder.parse(new File("/widgets.xml"));
//Get an XPath object and evaluate the expression
XPath xpath = XPathFactory.newInstance().newXPath();
String expression = "/widgets/widget";
Node widgetNode = (Node) xpath.evaluate(expression, document, XPathConstants.NODE);
//or using the evaluateExpression method
Node widgetNode = xpath.evaluateExpression(expression, document, Node.class);
</pre>
</blockquote>
<p>With a reference to the <code>&lt;widget&gt;</code> element, a
relative XPath expression can now written to select the
relative XPath expression can be written to select the
<code>&lt;manufacturer&gt;</code> child element:</p>
<blockquote>
<pre>
XPath xpath = XPathFactory.newInstance().newXPath();
<strong>String expression = "manufacturer";</strong>
Node manufacturerNode = (Node) xpath.evaluate(expression, <strong>widgetNode</strong>, XPathConstants.NODE);
</pre>
<ul>
<li>Author <a href="mailto:Ben@galbraiths.org">Ben Galbraith</a></li>
<li>Author <a href="mailto:Norman.Walsh@Sun.com">Norman Walsh</a></li>
<li>Author <a href="mailto:Jeff.Suttor@Sun.com">Jeff Suttor</a></li>
<li>See <a href="http://www.w3.org/TR/xpath">XML Path Language (XPath) Version 1.0</a></li>
<li>Since 1.5</li>
</ul>
//or using the evaluateExpression method
Node manufacturerNode = xpath.evaluateExpression(expression, <strong>widgetNode</strong>, Node.class);
</pre>
</blockquote>
<p>
In the above example, the XML file is read into a DOM Document before being passed
to the XPath API. The following code demonstrates the use of InputSource to
leave it to the XPath implementation to process it:
<blockquote>
<pre>
XPath xpath = XPathFactory.newInstance().newXPath();
String expression = "/widgets/widget";
InputSource inputSource = new InputSource("widgets.xml");
NodeList nodes = (NodeList) xpath.evaluate(expression, inputSource, XPathConstants.NODESET);
//or using the evaluateExpression method
XPathNodes nodes = xpath.evaluate(expression, inputSource, XPathNodes.class);
</pre>
</blockquote>
<p>
In the above cases, the type of the expected results are known. In case where
the result type is unknown or any type, the {@link javax.xml.xpath.XPathEvaluationResult}
may be used to determine the return type. The following code demonstrates the usage:
<blockquote>
<pre>
XPathEvaluationResult&lt;?&gt; result = xpath.evaluateExpression(expression, document);
switch (result.type()) {
case NODESET:
XPathNodes nodes = (XPathNodes)result.value();
...
break;
}
</pre>
</blockquote>
<p>
The XPath 1.0 Number data type is defined as a double. However, the XPath
specification also provides functions that returns Integer type. To facilitate
such operations, the XPath API allows Integer and Long to be used in
{@code evaluateExpression} method such as the following code:
<p>
<blockquote>
<pre>
int count = xpath.evaluate("count(/widgets/widget)", document, Integer.class);
</pre>
</blockquote>
@since 1.5
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